Primary Central Nervous System Lymphoma in a Patient with Down Syndrome.

Intracranial tumors are rare in persons with Down syndrome. Although germ cell tumors and gliomas have been reported in Down syndrome, primary central nervous system lymphoma (PCNSL) has not. We report a case of PCNSL in a 48-year-old man with Down syndrome and no history of malignant tumors. He visited our hospital for evaluation of left hemiparesis and gait disturbance. A thorough examination revealed brain tumors, and analysis of a biopsy specimen of the tumor confirmed a diagnosis of PCNSL. The final pathological diagnosis was diffuse large B-cell lymphoma of the central nervous system. Chemotherapy with rituximab, methotrexate, procarbazine, and vincristine was administered, and whole-brain irradiation was planned in conjunction with chemotherapy. It is unclear whether chromosomal abnormalities related to Down syndrome were involved in the development of PCNSL. Further molecular biological analysis may clarify the mechanism of combined Down syndrome and PCNSL.